403 Forbidden to access

Hi,
I am working with a charity to update their website and make it easier to keep up to date, but I am unable to install wordpress.
I have put it in the directory \devel\ so I can build it while the old site is active.

When running the setup here ( https://www.eastgrinsteadlions.org.uk/devel/wp-admin/install.php ) All i get is 403 Forbidden You don’t have permission to access /devel/wp-admin/install.php on this server.

I have looked at the .htaccess file, but I am unable to edit this.